Method and apparatus for transmitting and receiving an uplink acknowledgement channel for a downlink data channel in  a mobile communication system using orthogonal frequency division multiple access

ABSTRACT

A communication apparatus and method of a mobile communication system using Orthogonal Frequency-Division Multiple Access (OFDMA). A method of transmitting an uplink acknowledge channel (ACKCH) for a downlink data channel in a mobile communication system using OFDMA includes: determining channel resources for each Control Channel Element (CCE), when a downlink control channel including at least two CCEs is received; generating uplink acknowledgement information by analyzing a received downlink data channel; assigning the at least two CCEs to at least two transmission antennas, respectively; and transmitting the uplink ACKCH including the uplink acknowledgement information through the transmission antennas.

PRIORITY

This application claims priority to an application filed in the KoreanIntellectual Property Office on Aug. 5, 2008 and assigned Serial No.10-2008-0076343, the content of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a communication apparatus andmethod of a mobile communication system using OrthogonalFrequency-Division Multiple Access (OFDMA), and more particularly, to amethod and apparatus for transmitting and receiving an uplinkacknowledgement channel for a downlink data channel.

2. Description of the Related Art

In general, in a mobile communication system, Hybrid Automatic Repeatrequest (HARQ) is an important technology used to increase thereliability of data transmission and the data throughput in apacked-based mobile communication system. HARQ refers to a technologyobtained by combining the Automatic Repeat Request (ARQ) technology withthe Forward Error Correction (FEC) technology.

FIG. 1 is a diagram illustrating an example of a typical HARQ. In FIG.1, the horizontal axis is a time axis.

Referring to FIG. 1, in a mobile communication system, a base stationtransmits a plurality of data channels, and a terminal receives data bydemodulating the data channels. Here, the base station can repeatedlytransmit the same data or consecutively transmit different data throughthe data channels.

The base station performs an initial transmission operation 101 for aspecific data channel. The terminal apparatus that receives the initialtransmission data attempts to demodulate the data channel. In thisprocess, the terminal performs a Cyclic Redundancy Check (CRC) for thedata channel. If, as a result of the check, the initial transmissiondata is determined not to have been successfully demodulated, theterminal feedbacks Non-Acknowledgement (NACK) 102 to the base station.When the NACK 102 is received, the base station performs a firstretransmission operation 103, as a retransmission for the initialtransmission operation 101. Thus, the data channels in the initialtransmission operation 101 and the first retransmission operation 103transmit the same data. It should be noted that, although the datachannels transmit the same data, they may include differentredundancies.

It is assumed that the data transmission operations for the sameinformation, that is, each of the transmission operations 101, 103, 105,or 107 for the same information is called a sub-packet. The terminalthat receives the first retransmission 103 combines the receivedretransmitted data and the initially transmitted date the received inthe initial transmission 101 in accordance with a predetermined rule,and attempts to demodulate the data channels based on the combinedresult.

When the data transmission is not successfully demodulated through CRCfor the data channels in the above process, the terminal feedbacks aNACK 104 to the base station. The base station receives the NACK 104,and then performs a second retransmission operation 105, after a lapseof a given time from the first retransmission operation 103.

Thus, all the data channels for the initial transmission operation 101,the first retransmission operation 103, and the second retransmissionoperation 105 transmit the same information.

After the terminal receives the second retransmission data, the terminalperforms combining with respect to the initial transmission data, thefirst retransmission data, and the second retransmission data inaccordance with a predetermined rule, and demodulates the data channelsbased on the combining result.

As illustrated in FIG. 1, it is assumed that the data is successfullydemodulated through CRC for the data channels, after the secondretransmission 105.

Accordingly, after successful demodulation, the terminal feedbacks anACK 106 to the data base station. The base station receives the ACK 106,and performs an initial transmission 107 for a sub-packet of a next datainformation. The initial transmission operation 107 can be performedimmediately after the ACK 106 is received, or after a given time haselapsed, which results from a predetermined scheduling result.

As described above, in order to support HARQ, a terminal should transmitACK/NACK feedbacks. A channel that transmits the ACK/NACK is called aresponse channel, or ACK CHannel (ACKCH).

FIG. 2 is a diagram illustrating a Physical Downlink Control CHannel(PDCCH) and a Physical Uplink Control CHannel (PUCCH) of a conventionalmobile communication system.

Referring to FIG. 2, a base station configures PDCCHs 202 to 204 usingat least one Control Channel Element (CCE) 201 to transmit. Here, asingle PDCCH can use one, two, four, or eight CCEs 201. As illustratedin FIG. 2, each of the PDCCHs 202 to 204 can be used as a Down Link (DL)Grant. That is, the PDCCHs 202 to 204 can be used to allocate theresources of a Physical Downlink Shared CHannel (PDSCH) (i.e., adownlink data channel).

A terminal assigned with the resources of the PDSCH through the PDCCHs202 to 204 transmits ACK/NACK information through channel resources foran ACKCH 206, which is mapped to the first CCE 201 of each PDCCH withrespect to data transmitted through the allocated PDSCH resources. As anexample of the above method, an ACKCH 1 is composed of channel resourcescalled an ACKCH R1. Here, the channel resources refer to a Cyclic Shift(CS) and an Orthogonal Cover (OC) for configuring the ACKCH 206. Theterminal can determine a CS and an OC, which are the resources of theACKCH 206, using a channel index mapped to the CCE 201, as shown inTable 1 below.

TABLE 1 Resource allocation: 18ACK/NACK channels with normal CP CELLSPECIFIC RS ACK/NACK CYCLIC SHIFT OFFSET ORTHOGONAL COVER ORTHOGONALCOVER δ_(offset) ^(PUCCH) = 1 δ_(offset) ^(PUCCH) = 0 n _(oc) = 0 n_(oc) = 1 n _(oc) = 2 n_(oc) = 0 n_(oc) = 1 n_(oc) = 2 n_(cs) = 1 n_(cs)= 0 n′ = 0 12 n′ = 0 12 2 1 6 6 3 2 1 13 1 13 4 3 7 7 5 4 2 14 2 14 6 58 8 7 6 3 15 3 15 8 7 9 9 9 8 4 16 4 16 10 9 10 10 11 10 5 17 5 17 0 1111 11

Table 1 illustrates configurations of 18 ACKCHs in order to minimizeinterference of each sequence when a normal Cyclic Prefix (CP) is used.For example, when a channel index mapped to the CCE 201 is 5 and apreset δ_(offset) ^(PUCCH) is 0, the terminal generates the ACKCH 206using CS=10 and OC=0.

FIG. 3 is a diagram illustrating an ACKCH configuration using a CS andan OC, which are resources of an ACKCH corresponding to each index.

Referring to FIG. 3, as to the ACK/NACK information, aComputer-Generated (CG) sequence is generated using an allocated CS. Thegenerated sequence is copied into four sequences. Each of the fourcopied sequences passes through Inverse Fast Fourier Transforms (IFFTs)301, is multiplied by one bit of an OC by multipliers 302, and is thenmapped 303 to each symbol of resource block allocated to a PUCCH. Themapped ACK/NACK symbol, together with uplink reference signal symbols,is hopped to each of slots within one sub-frame through one antenna, sothat the same seven symbols are mapped.

The PDCCH includes one or several CCEs in order to transmit informationhaving a different length according to the property of a DL grant and toincrease the reliability of PDCCH depending on channel conditions byusing a different number of CCEs according to channel conditions.However, assuming that channel resources are allocated to CCEs of PDCCH,respectively, when uplink ACK/NACK is transmitted, the channel resourcesshould be allocated with the same number as CCEs. However, when thePDCCH includes several CCEs, the efficiency of resources decreasesbecause only the first channel resource among uplink channel resourcesmapped to the CCEs is used and the remaining channel resources are notused.

SUMMARY OF THE INVENTION

The present invention has been designed in view of at least the aboveproblems and provides a method and apparatus, which are capable of usinguplink resources efficiently and using a plurality of antennas in amobile communication system using Orthogonal Frequency-Division MultipleAccess.

The present invention further provides a method and apparatus fortransmitting an uplink ACKCH for a downlink data channel in a mobilecommunication system using Orthogonal Frequency-Division MultipleAccess.

In accordance with an aspect of the present invention, a method oftransmitting an uplink ACKnowledge CHannel (ACKCH) for a downlink datachannel in a mobile communication system using OrthogonalFrequency-Division Multiple Access (OFDMA) includes: determining channelresources for each Control Channel Element (CCE), when a downlinkcontrol channel including at least two CCEs is received; generatinguplink acknowledgement information by analyzing a received downlink datachannel; assigning the CCEs to at least two transmission antennas insuch a manner that the CCEs correspond to the transmission antennas; andtransmitting the uplink ACKCH as the uplink acknowledgement informationthrough the transmission antennas.

In accordance with another aspect of the present invention, a method ofreceiving an uplink ACKCH for a downlink data channel from atransmission apparatus in a mobile communication system using OFDMAincludes: transmitting a downlink control channel including at least twoCCEs; selecting reception antennas with a number corresponding to anumber of CCEs and assigning the selected reception antennas to thechannel resources in such a manner that the reception antennascorrespond to the channel resources by CCE, when the number of CCEs is anumber of transmission antennas of the transmission apparatus and less;and receiving the uplink ACKCH through the reception antennas.

In accordance with another aspect of the present invention, an apparatusfor transmitting an uplink ACKCH for a downlink data channel in a mobilecommunication system using OFDMA includes: a transmission module thatdetermines channel resources by CCE and generates uplink acknowledgementinformation by analyzing a received downlink data channel, when adownlink control channel including at least two CCEs is received; aplurality of transmission antennas that transmits the uplinkacknowledgement information; and a controller that assigns the CCEs toat least two transmission antennas in such a manner that the CCEscorrespond to the transmission antennas, and transmits the uplink ACKCHas the uplink acknowledgement information through the transmissionantennas.

In accordance with another aspect of the present invention, an apparatusfor receiving an uplink ACKCH for a downlink data channel from atransmission apparatus in a mobile communication system using OFDMAincludes: a plurality of reception antennas that receives a downlinkcontrol channel including at least two CCEs and uplink acknowledgementinformation corresponding to the downlink data channel from at least twotransmission antennas of the transmission apparatus; and a controllerthat selects the reception antennas with a number corresponding to anumber of CCEs and assigns to correspond to the channel resources byCCE, and receives the uplink acknowledgement information from the uplinkACKCH through the reception antennas, when the number of CCEs is thenumber of transmission antennas or less.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will be more apparent from the following detailed descriptionin conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram illustrating an example of a typical HARQ;

FIG. 2 is a diagram illustrating a Physical Downlink Control Channel anda Physical Uplink Control Channel of a mobile communication system;

FIG. 3 is a diagram illustrating an ACKCH configuration using a CS andan OC, which are resources of an ACKCH corresponding to each index;

FIG. 4 is a diagram illustrating a method of transmitting a physicaluplink acknowledge channel according to an embodiment of the presentinvention;

FIGS. 5A to 5D are diagrams illustrating methods of transmittingACK/NACK information according to a number of transmission antennasusing CSs and OCs, which are channel resources set according to a numberof CCEs constituting a PDCCH according to embodiments of the presentinvention;

FIG. 6 is a diagram illustrating a transmission apparatus fortransmitting ACK/NACK information through a plurality of transmissionantennas in a mobile communication system according to an embodiment ofthe present invention;

FIGS. 7A to 7D are flowcharts illustrating methods of transmittingACK/NACK information according to the number of CCEs of PDCCH and thenumber of transmission antennas according to embodiments of the presentinvention;

FIG. 8 is a diagram illustrating a reception apparatus for receivingACK/NACK information in a mobile communication system according to anembodiment of the present invention; and

FIGS. 9A to 9D are flowcharts illustrating methods of receiving ACK/NACKinformation according to the number of CCEs of PDCCH and the number oftransmission antennas according to embodiments of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE PRESENT INVENTION

Embodiments of the present invention are described in detail below withreference to the accompanying drawings. The same reference numbers areused throughout the drawings to refer to the same or like parts.Further, detailed descriptions of well-known functions and structuresincorporated herein may be omitted to avoid obscuring the subject matterof the present invention.

As described above, HARQ is an important technique for increasing thereliability of data transmission and the data throughput in apacked-based mobile communication system. Further, in order to supportHARQ, a terminal should transmit ACK/NACK feedbacks. Herein, a channelthat transmits the ACK/NACK information in the terminal will be referredto as an ACK CHannel (ACKCH).

FIG. 4 is a diagram illustrating a method of transmitting a physicaluplink ACKCH according to an embodiment of the present invention.

Referring to FIG. 4, a terminal transmits uplink acknowledgementinformation (i.e., ACK/NACK information) about a PDSCH to a base stationthrough uplink ACKCHs, which are assigned based on the CCEs of the PDCCHaccording to an embodiment of the present invention. Here, the terminalcan transmit the same ACKCHs to the base station in response to aspecific PDSCH using a plurality of channel resources.

More specifically, the terminal transmits ACKCH1 to ACKCH5 411, 412,414, 415, and 417 using respective channel resources, that is, ACKCH R1401, ACKCH R2 402, ACKCH R4 404, ACKCH R5 405, and ACKCH R7 407, whichare mapped to the first CCE of the PDCCH. When the PDCCH includes aplurality of CCEs, the terminal transmits ACKCH1 to ACKCH5 413, 416,418, 419, and 420 using respective channel resources, that is, ACKCH R3403, ACKCH R6 406, ACKCH R8 408, ACKCH R9 409, and ACKCH R10 410 whichare mapped to CCEs except for the first CCE of the PDCCH. The terminaltransmits the ACKCHs through a plurality of transmission antennas. Inthis case, the terminal assigns channel resources, which are differentfor every slot, to the respective transmission antennas in a pluralityof the slots constituting the ACKCH, and then transmits the ACKCHs.

For example, since a PDCCH1 423 is composed of one CCE (i.e. CCE1 421),the terminal transmits the ACKCH1 411 for the PDSCH using the ACKCH R1401, which are channel resources mapped to the CCE1 421. Here, theterminal transmits the ACKCH1 411 through one or more transmissionantennas using only one channel resource. On the other hand, since aPDCCH2 424 includes two CCEs (i.e., a CCE2 and a CCE3 422), the terminaltransmits the ACKCH2 s 412 and 413 for the PDSCH using the ACKCH R2 402and the ACKCH R3 403, which are respectively mapped to the CCE2 and theCCE3 422. Here, the terminal transmits ACKCH2 s 412 and 413 through aplurality of transmission antennas using the two channel resources.

When the number of CCEs constituting the PUCCH is equal to or less thanthe number of the transmission antennas, the number of transmissionantennas used corresponds to the number of CCEs to transmit the ACKCH.

FIGS. 5A to 5D are diagrams illustrating methods of transmittingACK/NACK information according to a number of transmission antennasusing CSs and OCs, which are channel resources set according to a numberof CCEs constituting a PDCCH, according to embodiments of the presentinvention.

FIG. 5A is a diagram illustrating a method of transmitting ACK/NACKinformation from a terminal using one channel resource mapped to a PDCCHthrough two transmission antennas, while the PDCCH is composed of oneCCE, according to an embodiment of the present invention.

Referring to FIG. 5A, one ACK/NACK information is processed using one CSand one OC, which are one channel resource as illustrated in FIG. 3, andis then, as a first example, transmitted through two transmissionantennas using an antenna selection method that transmits the sameinformation to a first antenna in a slot 1 and to a second antenna in aslot 2.

As a second example, data can be transmitted using a Precoding VectorSwitching (PVS) method, wherein the same information is transmittedthrough two slots, while the same information is transmitted aftermultiplying [1.1] in the first antenna and after multiplying [1.-1] inthe second antenna. Accordingly, the same information is transmittedwhile maintaining orthogonality.

FIG. 5B is a diagram illustrating a method of transmitting ACK/NACKinformation of terminal using two transmission antennas while a PDCCH iscomposed of two CCEs, according to an embodiment of the presentinvention.

Referring to FIG. 5B, the same ACK/NACK information is processed into asignal to be transmitted respectively using two CSs and two OCs, whichare channel resources mapped to two CCEs, and is then repeatedlytransmitted through a slot 1 and a slot 2 through each of the twotransmission antennas. That is, the ACK/NACK information using the firstchannel resource is transmitted through the first antenna, while theACK/NACK information using the second channel resource is transmittedthrough the second antenna.

FIG. 5C is a diagram illustrating a method of transmitting ACK/NACKinformation of terminal using four transmission antennas while a PDCCHis composed of two CCEs, according to an embodiment of the presentinvention.

Referring to FIG. 5C, in ACK/NACK information generated using twochannel resources, one ACK/NACK information is transmitted through twotransmission antennas. One ACK/NACK information is transmitted throughtwo transmission antennas using the antenna selection method or the PVSmethod in the same manner as illustrated in FIG. 5A. That is, theACK/NACK information is processed into signals using two channelresources and is then transmitted through antennas 1&2 and 3&4 using theantenna selection method or the PVS method.

FIG. 5D is a diagram illustrating a method of transmitting ACK/NACKinformation of terminal using four antennas while a PDCCH is composed offour CCEs, according to an embodiment of the present invention. Morespecifically, the ACK/NACK information is transmitted through each ofthe transmission antennas using four channel resources.

When the number of CCEs constituting the PUCCH exceeds the number oftransmission antennas, the ACKCH is transmitted using the same number ofCCEs corresponding to the available number of transmission antennas.Otherwise, the ACKCH is transmitted using the as many CCEs as half ofthe number of available transmission antennas. At this time, the ACKCHcan be transmitted with the PVS method using the channel resource of oneCCE for two transmission antennas.

Table 2 indicates that a terminal transmits the ACKCH informationthrough two or four transmission antennas with the PVS method using fourchannel resources, while a PDDCH includes four CCES. A first selectioncan be performed using a third and a fourth channel resource and sixselection methods can be used with the same method. That is, thefollowing Table 2 indicates a scenario in which only two channelresources are used among four channel resources.

TABLE 2 example of channel channel channel channel selection resource 1resource 2 resource 3 resource 4 1 0 0 1 1 2 0 1 0 1 3 0 1 1 0 4 1 0 0 15 1 0 1 0 6 1 1 0 0

Table 3 indicates that a terminal transmits the ACKCH informationthrough two or four transmission antennas with the PVS method usingeight channel resources, while a PDDCH includes eight CCES. A firstselection can be performed using a seventh and an eighth channelresource, while twenty-eight selection methods can be used with the samemethod. That is, the following Table 3 indicates a scenario in whichonly two channel resources are used among eight channel resources.

TABLE 3 example of channel channel channel channel channel channelchannel channel selection resource 1 resource 2 resource 3 resource 4resource 5 resource 6 resource 7 resource 8 1 0 0 0 0 0 0 1 1 2 0 0 0 00 1 0 1 3 0 0 0 0 0 1 1 0 4 0 0 0 0 1 0 0 1 5 0 0 0 0 1 0 1 0 6 0 0 0 01 1 0 0 7 0 0 0 1 0 0 0 1 8 0 0 0 1 0 0 1 0 9 0 0 0 1 0 1 0 0 10 0 0 0 11 0 0 0 11 0 0 1 0 0 0 0 1 12 0 0 1 0 0 0 1 0 13 0 0 1 0 0 1 0 0 14 0 01 0 1 0 0 0 15 0 0 1 1 0 0 0 0 16 0 1 0 0 0 0 0 1 17 0 1 0 0 0 0 1 0 180 1 0 0 0 1 0 0 19 0 1 0 0 1 0 0 0 20 0 1 0 1 0 0 0 0 21 0 1 1 0 0 0 0 022 1 0 0 0 0 0 0 1 23 1 0 0 0 0 0 1 0 24 1 0 0 0 0 1 0 0 25 1 0 0 0 1 00 0 26 1 0 0 1 0 0 0 0 27 1 0 1 0 0 0 0 0 28 1 1 0 0 0 0 0 0

Table 4 indicates that a terminal transmits the ACKCH informationthrough four or eight channel resources using eight channel resources,while a PDDCH includes eight CCES. A first selection can be performedusing a fifth, a sixth, a seventh, and an eighth channel resource, andseventy selection methods can be used with the same method. That is, thefollowing Table 4 indicates a scenario in which only four channelresources are used among eight channel resources.

TABLE 4 example of channel channel channel channel channel channelchannel channel selection resource 1 resource 2 resource 3 resource 4resource 5 resource 6 resource 7 resource 8 1 0 0 0 0 1 1 1 1 2 0 0 0 10 1 1 1 3 0 0 0 1 1 0 1 1 4 0 0 0 1 1 1 0 1 5 0 0 0 1 1 1 1 0 6 0 0 1 00 1 1 1 7 0 0 1 0 1 0 1 1 8 0 0 1 0 1 1 0 1 9 0 0 1 0 1 1 1 0 10 0 0 1 10 0 1 1 11 0 0 1 1 0 1 0 1 12 0 0 1 1 0 1 1 0 13 0 0 1 1 1 0 0 1 14 0 01 1 1 0 1 0 15 0 0 1 1 1 1 0 0 16 0 1 0 0 0 1 1 1 17 0 1 0 0 1 0 1 1 180 1 0 0 1 1 0 1 19 0 1 0 0 1 1 1 0 20 0 1 0 1 0 0 1 1 21 0 1 0 1 0 1 0 122 0 1 0 1 0 1 1 0 23 0 1 0 1 1 0 0 1 24 0 1 0 1 1 0 1 0 25 0 1 0 1 1 10 0 26 0 1 1 0 0 0 1 1 27 0 1 1 0 0 1 0 1 28 0 1 1 0 0 1 1 0 29 0 1 1 01 0 0 1 30 0 1 1 0 1 0 1 0 31 0 1 1 0 1 1 0 0 32 0 1 1 1 0 0 0 1 33 0 11 1 0 0 1 0 34 0 1 1 1 0 1 0 0 35 0 1 1 1 1 0 0 0 36 1 0 0 0 0 1 1 1 371 0 0 0 1 0 1 1 38 1 0 0 0 1 1 0 1 39 1 0 0 0 1 1 1 0 40 1 0 0 1 0 0 1 141 1 0 0 1 0 1 0 1 42 1 0 0 1 0 1 1 0 43 1 0 0 1 1 0 0 1 44 1 0 0 1 1 01 0 45 1 0 0 1 1 1 0 0 46 1 0 1 0 0 0 1 1 47 1 0 1 0 0 1 0 1 48 1 0 1 00 1 1 0 49 1 0 1 0 1 0 0 1 50 1 0 1 0 1 0 1 0 51 1 0 1 0 1 1 0 0 52 1 01 1 0 0 0 1 53 1 0 1 1 0 0 1 0 54 1 0 1 1 0 1 0 0 55 1 0 1 1 1 0 0 0 561 1 0 0 0 0 1 1 57 1 1 0 0 0 1 0 1 58 1 1 0 0 0 1 1 0 59 1 1 0 0 1 0 0 160 1 1 0 0 1 0 1 0 61 1 1 0 0 1 1 0 0 62 1 1 0 1 0 0 0 1 63 1 1 0 1 0 01 0 64 1 1 0 1 0 1 0 0 65 1 1 0 1 1 0 0 0 66 1 1 1 0 0 0 0 1 67 1 1 1 00 0 1 0 68 1 1 1 0 0 1 0 0 69 1 1 1 0 1 0 0 0 70 1 1 1 1 0 0 0 0

FIG. 6 is a diagram illustrating a transmission apparatus fortransmitting ACK/NACK information through a plurality of transmissionantennas in a mobile communication system according to an embodiment ofthe present invention.

Referring to FIG. 6, the transmission apparatus includes a plurality oftransmission modules 610, 620, 630, and 640, a controller 600, adistributor/selector 650, and a plurality of transmitters 661, 662, 663,and 664.

Each of the transmission modules 610, 620, 630, and 640 determineschannel resources using the CCE of PDCCH, i.e., the CS and the OC,generates uplink acknowledgement information (i.e., ACK/NACKinformation) based on an analysis result of the PDSCH, and performsprocessing using the CS and the OC.

The first transmission module 610 includes a PUCCH transmission unit611, a PUSCH transmission unit 612, an IFFT unit 613, and a CPprocessing unit 614. The PUCCH transmission unit 611 processes receivedACK/NACK information using one CS and one OC. The PUSCH transmissionunit 612 processes generated PUSCH data. The IFFT unit 613 performs IFFTon the PUCCH and the PUSCH data, and the CP processing unit 614 adds aCP to the output of the IFFT unit 613.

The second transmission module 620 to the fourth transmission module 640have the same configuration as the first transmission module 610, andare configured to process the respective data of transmission modulesusing the same method as the first transmission module 610. Accordingly,a description of these transmission modules will not be repeated.

The controller 600 controls an operation for selecting and distributingthe outputs of the first transmission module 610 to fourth transmissionmodule 640 according to the number of CCEs of a PDCCH and an inputsignal for mode selection signal (mode selection between antennaselection/precoding vector switching. Here, the controller 600 comparesthe number of CCEs with the number of transmission antennas, and selectsand distributes the outputs of the first transmission module 610 tofourth transmission module 640 based on the comparison result.

The distributor/selector 650 receives the outputs of the firsttransmission module 610 to fourth transmission module 640, anddistributes and selects the outputs of the first transmission module 610to fourth transmission module 640 under the control of the controller600. Here, the distributor/selector 650 assigns different channelresources to respective transmission antennas. For example, when thenumber of CCEs is identical to the number of transmission antennas, thedistributor/selector 650 assigns channel resources to the transmissionantennas on a one-to-one basis. However, when the number of CCEs exceedsthe number of transmission antennas, the distributor/selector 650selects as many channel resources as there transmission antennas, andassigns the channel resources to the respective transmission antennas.Furthermore, when the number of CCEs is less than the number oftransmission antennas, the distributor/selector 650 selects the atransmission antenna for each of the CCEs, and assigns the channelresources to the respective transmission antennas. Further, thedistributor/selector 650 transmits the ACK/NACK information through atleast any one of transmission antennas.

Each of the transmitters 661 to 664 includes a transmission antenna(Antenna 1 to a Antenna 4, respectively) and transforms a transmissionsignal of baseband output from the distributor/selector 650 into a RFsignal and outputs the transformed signal through a correspondingtransmission antenna.

As described above, after one ACK/NACK information is processed usingone CS and one OC in the PUCCH transmission unit 611 of the transmissionmodules 610, 620, 630, and 640, IFFT and the CP addition are performedalong with the output of the PUSCH transmission unit 612. The aboveprocesses are processed in the transmission modules 610, 620, 630, and640 that use one CS and one OC, while these transmission modules 610,620, 630, and 640 are implemented as many as the number of CCEs used ina PDCCH.

Further, each of the transmission modules 610, 620, 630, and 640generates signals to be transmitted to each of the transmission antennasthrough the distributor/selector 650 by using the number of CCEsconstituting a PDCCH and a signal generated in the controller 600 thatoperates according to the antenna selection method or the PVS method,and transmits the signal through each transmission antennas.

FIGS. 7A to 7D are flowcharts illustrating methods of a transmissionapparatus transmitting ACK/NACK information according to a number oftransmission antennas and a number of CCEs included in a PDCCH,according to embodiments of the present invention.

In FIGS. 7A to 7D, the transmission apparatus checks the number of CCEsincluded in the PDCCH and performs a pertinent procedure according tothe number of CCEs. When there is 1 CCE, the transmission apparatusperforms a procedure as illustrated in FIG. 7A. When there are 2 CCEs,the transmission apparatus performs a procedure as illustrated in FIG.7B. When there are 4 CCEs, the transmission apparatus performs aprocedure as illustrated in FIG. 7C. When there are 8 CCEs, thetransmission apparatus performs a procedure as illustrated in FIG. 7 d.

Referring to FIG. 7A, the transmission apparatus checks a number of CCEsincluded in a PDCCH in step 712. When the number of CCEs is one, theterminal (i.e., the transmission apparatus) checks a number oftransmission antennas in step 714. When the number of transmissionantennas is one, the terminal transmits one ACK/NACK information usingone CS and one OC, which are the same channel resources, through asingle transmission antenna in step 718. However, if the number oftransmission antennas is two, the terminal transmits one ACK/NACKinformation using one CS and one OC, which are the same channelresources, through two transmission antennas according to the antennaselection method/the PVS method in step 716.

As illustrated in FIG. 7A, the terminal performs a different ACK/NACKtransmission method based on the number of transmission antennas to betransmitted. When a single transmission antenna can be used, theterminal transmits one ACK/NACK information using one CS and one OCthrough a single transmission antenna. However, when two transmissionantennas are supported, the terminal transmits one ACK/NACK informationusing one CS and one OC through the two transmission antennas, accordingto the antenna selection method or the PVS method.

FIG. 7B is a flowchart of transmitting ACK/NACK information of terminalhaving one, two, or four transmission antennas, wherein the PDCCHincludes two CCEs, according to an embodiment of the present invention.

Referring to FIG. 7B, if the number of CCEs included in the PDCCH isdetermined to be two at step 712 of FIG. 7A, the terminal checks thenumber of transmission antennas in step 722. When there is onetransmission antenna, the transmission apparatus transmits one ACK/NACKinformation using one CS and one OC, which are a single channelresource, through the one transmission antenna in the same manner as theexisting LTE system in step 724. For example, the transmission apparatuscan transmit ACK/NACK information using a channel resource that ismapped to the first CCE of a PDCCH.

However, when there are two transmission antennas in step 722, theterminal transmits one ACK/NACK information using two CSs and two OCs,which are two channel resources, through two transmission antennas instep 726.

However, when there are four transmission antennas in step 722, theterminal transmits one ACK/NACK information using two CSs and two OCs,which are two channel resources, through the four transmission antennasin step 728. The ACKCH that has passed one channel resource istransmitted to two transmission antennas using the antenna selectionmethod or the PVS method.

As illustrated in FIG. 7B, when the PDCCH includes two CCEs, a terminalcan transmit one ACK/NACK information using two channel resources.However, a terminal having one transmission antenna transmits oneACK/NACK information using one CS and one OC through the singletransmission antenna in the same manner as the existing LTE system. Whenthere are two transmission antennas, one ACK/NACK information istransmitted using two CSs and two OCs, which are two channel resources,through two transmission antennas. Further, when there are fourtransmission antennas, one ACK/NACK information is transmitted usinginformation that is generated using two CSs and two OCs, which are twochannel resources and two channel resources, through the fourtransmission antennas according to the antenna selection method or thePVS method.

FIG. 7C is a flowchart of control according to one, two, or fourtransmission antennas in a terminal when the PDCCH includes four CCEs,according to an embodiment of the present invention.

Referring to FIG. 7C, when the number of CCEs included in the PDCCH isdetermined to be four at step 712 of FIG. 7A, the terminal checks anumber of transmission antennas in step 732. When there is onetransmission antennas in step 732, the transmission apparatus transmitsone ACK/NACK information using one CS and one OC, which are one channelresource, through the one transmission antenna in the same manner as theexisting LTE system in step 734. For example, the transmission apparatuscan transmit ACK/NACK information using a channel resource that ismapped to the first CCE of a PDCCH.

However, when there are two transmission antennas in step 732, theterminal transmits one ACK/NACK information using two CSs and two OCs,which are two channel resources, through the two antennas in step 736.

When there are four transmission antennas in step 732, the terminaltransmits one ACK/NACK information using four CSs and four OCs, whichare four channel resources, through the four antennas in step 738. TheACKCH that has passed one channel resource is transmitted to twoantennas using the antenna selection method or the PVS method.

As illustrated in FIG. 7C, when the PDCCH having four CCEs is used, thetransmission apparatus can use four CSs and four OCs, which are fourchannel resources. When a terminal has one transmission antenna, oneACK/NACK information is transmitted using one CS and one OC, which areone channel resource, through the one transmission antenna in the samemanner as the existing LTE system. When a terminal has two transmissionantennas, as shown in the above Table 2, one ACK/NACK information istransmitted using two CSs and two OCs, which are two channel resources,through the two transmission antennas. Further, when a terminal has fourtransmission antennas, one ACK/NACK information is transmitted usingfour CSs and four OCs, which are four channel resources, through thefour transmission antennas.

FIG. 7D is a flowchart of control according to one, two, or fourtransmission antennas in a terminal when the PDCCH includes eight CCEs,according to an embodiment of the present invention.

Referring to FIG. 7D, if eight CCEs are included in the PDCCH in step712 of FIG. 7A, the terminal checks a number of transmission antennas instep 742. When there is one transmission antenna in step 742, thetransmission apparatus transmits one ACK/NACK information using one CSand one OC, which are one channel resource, through the one transmissionantenna in the same manner as the existing LTE system (744). Forexample, the transmission apparatus can transmit ACK/NACK informationusing a channel resource that is mapped to the first CCE of a PDCCH.

However, when there are two transmission antennas in step 742, theterminal transmits one ACK/NACK information using two CSs and two OCs,which are two channel resources, through two transmission antennas instep 746.

In addition, when there are four transmission antennas in step 742, theterminal transmits one ACK/NACK information using four CSs and four OCs,which are four channel resources, through the four antennas in step 748.

In an LTE-A system, a maximum limit of reverse-direction transmissionantennas is set up to be four. Accordingly, as illustrated in FIG. 7D,when a PDCCH having eight CCEs is used, the transmission apparatusselects channel resources that will be used according to a number oftransmission antenna among eight channel resources matched to eightCCEs. When there is one transmission antenna, one ACK/NACK informationis transmitted using the channel resource matched to the first CCEthrough the one transmission antenna in the same manner as the existingLTE system. When there are two transmission antennas, as shown in theabove Table 3, one ACK/NACK information is transmitted using two channelresources among eight channel resources through the two transmissionantennas. When there are four transmission antennas, as shown in theabove Table 4, one ACK/NACK information is transmitted by using fourchannel resources among eight channel resources through the fourtransmission antennas.

FIG. 8 is a diagram showing a configuration of a reception apparatus forreceiving ACK/NACK information in a mobile communication systemaccording to an embodiment of the present invention.

Referring to FIG. 8, the reception apparatus includes a plurality ofreception modules 810, 820, 830, and 840, a controller 800, and aselector/combiner 850.

The reception modules 810, 820, 830, and 840 are equipped with, forexample, four reception antennas, respectively. The first receptionmodule 810 includes an RF reception unit 811, a CP eliminator 812, a FFTprocessing unit 813, a PUCCH reception unit 814, and a PUSCH receptionunit 815. The RF reception unit 811 down-converts an RF signal receivedfrom an antenna into a baseband frequency, and converts thefrequency-converted signal into digital data. The CP eliminator 812eliminates a CP from the output of the RF reception unit 811. The FFTprocessing unit 813 performs FFT on the output of the CP eliminator 812and outputs the FFT result. Furthermore, the PUCCH reception unit 814generates ACK/NACK information by processing PUCCH data using a CS andan OC, which are corresponding channel resources. Each of the secondreception modules 820 to fourth reception modules 840 has the sameconfiguration as the first reception module 810, and generates ACK/NACKinformation using respective CS and OC, which are channel resources.Accordingly, a description of these reception modules will not berepeated.

The controller 800 generates a control signal for selecting andcombining the first reception module 810 to fourth reception modules 840by comparing and analyzing the number of CCEs of PDCCH and the number oftransmission antennas of the transmission apparatus.

The selector/combiner 850 selects the output of the first receptionmodule 810 to fourth reception modules 840 among a plurality of outputsor combines at least part of the outputs of the first reception module810 to fourth reception modules 840 and outputs as final ACK/NACKinformation under the control of the controller 800.

The selector/combiner 850 assigns different channel resources torespective reception antennas. For example, when the number of CCEs isless than or equal to the number of transmission antennas, theselector/combiner 850 can select the same number of reception antennasas CCEs, and assign channel resources to the respective receptionantennas. Further, if the number of CCEs exceeds the number oftransmission antennas, the selector/combiner 850 can select as manychannel resources as the number of transmission antennas, and assignschannel resources to the respective reception antennas.

As described above, each of the reception modules 810 to 840frequency-converts and digital-converts the signals received from theplurality of reception antennas, removes CPs of the converted signal toperform a FFT process, and applies to the PUCCH reception unit 814 togenerate ACK/NACK information. The PUCCH reception unit 814 of each ofthe reception modules, which use CSs and OCs, which are respectivechannel resources, generates ACK/NACK information of a correspondingreception module using the respective channel resources, and applies tothe selector/combiner 850. Furthermore, the controller 800 that inputsinformation about the number of CCEs included in a PDCCH and the numberof transmission antennas of a terminal generates a signal forcontrolling the selector/combiner 850 by analyzing the information. Theselector/combiner 850 generates final ACK/NACK information by selectingand combining information generated using a plurality of channelresources in the first reception module 810 to fourth reception modules840 in response to the control signal of the controller 800.

FIGS. 9A to 9D are flowcharts illustrating methods of receiving ACK/NACKinformation according to a number of CCEs of PDCCH and a number oftransmission antennas, according to embodiments of the presentinvention.

In FIGS. 9A to 9C, the reception apparatus checks the number of CCEsincluded in the PDCCH. When there is one CCE, a procedure as illustratedin FIG. 9A is performed. When there are two CCEs, a procedure asillustrated in FIG. 9B is performed. When there are four CCEs, aprocedure as illustrated in FIG. 9C is performed. When there are eightCCEs, a procedure as illustrated in FIG. 9D is performed.

Referring to FIG. 9A, the reception apparatus checks the number of CCEsincluded in the PDCCH in step 912. When there is one CCE in step 912,the reception apparatus checks the number of transmission antennas of aterminal in step 914. When there is one transmission antenna in step914, the reception apparatus receives one ACKCH using one CS and one OC,which are one channel resource, through a plurality of receptionantennas in the same manner as the existing LTE system in step 916. Whenthere are two transmission antennas in step 914, the reception apparatusreceives one ACKCH using one CS and one OC, which are one channelresource through a plurality of reception antennas in step 918. TheACKCH that has passed one channel resource receives signals receivedusing respective channel resources using the antenna selection method orthe PVS method according to a transmit diversity method.

As described above, the method of receiving ACK/NACK information in thereception apparatus differs depending on an antenna transmission methodof the transmission apparatus. When the transmission apparatus uses onetransmission antenna, the reception apparatus receives one ACK/NACKinformation through a plurality of reception antennas using one CS andone OC, which are the same channel resource. When the transmissionapparatus uses two transmission antennas, the reception apparatusreceives one ACK/NACK information through a plurality of receptionantennas using one CS and one OC, which are the same channel resource,according to the antenna selection method or the PVS method.

FIG. 9B is a flowchart of receiving ACK/NACK information of thereception apparatus, when the PDCCH includes two CCEs and a transmissionapparatus includes one, two, or four transmission antennas, according toan embodiment of the present invention.

Referring to FIG. 9B, when there are two CCEs included in the PDCCH instep 912 of FIG. 9A, the base station checks the number of transmissionantennas of the transmission apparatus in step 922.

When there is one transmission antenna in step 922, the receptionapparatus receives one ACKCH through a plurality of reception antennasusing one CS and one OC, which are one channel resource, in the samemanner as the existing LTE system in step 924. For example, thereception apparatus can receive ACK/NACK information using a channelresource, which is mapped to the first CCE of the PDCCH.

When there are two transmission antennas in step 922, the receptionapparatus receives one ACKCH through a plurality of reception antennasusing two CSs and two OCs, which are two channel resources, in step 926.

When there are four transmission antennas in step 922, the receptionapparatus receives one ACKCH through a plurality of reception antennasusing two CSs and two OCs, which are two channel resources, in step 928.The ACKCH that has passed one channel resource receives signals usingrespective channel resources according to a transmit diversity methodusing the antenna selection method or the PVS method.

As illustrated in FIG. 9B, when the PDCCH includes two CCEs, thereception apparatus can receive one ACK/NACK information using twochannel resources. When the transmission apparatus includes onetransmission antenna, however, the reception apparatus receives onepiece of ACK/NACK information through a plurality of reception antennasusing one CS and one OC, which are one channel resource, in the samemanner as the existing LTE system. When the transmission apparatusincludes two transmission antennas, the reception apparatus receives oneACK/NACK information through a plurality of reception antennas using twoCSs and two OCs, which are two channel resources. When the transmissionapparatus includes four transmission antennas, the reception apparatusreceives one ACK/NACK information through a plurality of receptionantennas based on information, which is generated using two CSs and twoOCs, which are two channel resources according to the antenna selectionmethod or the PVS method.

FIG. 9C is a flowchart illustrating a control procedure of the receptionapparatus when the PDCCH includes four CCEs and a transmission apparatusincludes one, two, or four transmission antennas, according to anembodiment of the present invention.

Referring to FIG. 9C, when there are four CCEs included in the PDCCH instep 912 of FIG. 9A, the reception apparatus checks the number oftransmission antennas of the transmission apparatus in step 932. Whenthere is one transmission antenna in step 932, the reception apparatusreceives one ACKCH through a plurality of reception antennas using oneCS and one OC, which are one channel resource, in the same manner as theexisting LTE system in step 934. For example, the reception apparatuscan receive ACK/NACK information using a channel resource, which ismapped to the first CCE of the PDCCH.

When there are two transmission antennas in step 932, the receptionapparatus receives one ACKCH through a plurality of reception antennasusing two CSs and two OCs, which are two channel resources, in step 936.

When there are four transmission antennas in step 932, the receptionapparatus receives one ACKCH through a plurality of reception antennasusing four CSs and four OCs, which are four channel resources, in step938.

As illustrated in FIG. 9C, when the PDCCH includes four CCEs, thereception apparatus can use four CSs and four OCs, which are fourchannel resources. In this case, when the transmission apparatusincludes one transmission antenna, the reception apparatus receives oneACK/NACK information through a plurality of reception antennas using oneCS and one OC, which are one channel resource, in the same manner as theexisting LTE system. When the transmission apparatus includes twotransmission antennas, as shown in the above Table 2, one ACK/NACKinformation is received through a plurality of reception antennas usingtwo CSs and two OCs, which are two channel resources. When thetransmission apparatus includes four transmission antennas, one ACK/NACKinformation is received through a plurality of reception antennas usingfour CSs and four OCs, which are four channel resources.

FIG. 9D is a flowchart illustrating a control procedure of the receptionapparatus when the PDCCH includes eight CCEs and a transmissionapparatus includes one, two, or four transmission antennas, according toan embodiment of the present invention.

Referring to FIG. 9D, when there are eight CCEs included in the PDCCH instep 912 of FIG. 9A, the reception apparatus checks the number oftransmission antennas of the transmission apparatus in step 942. Whenthere is one transmission antenna in step 942, the reception apparatusreceives one ACKCH through a plurality of reception antennas using oneCS and one OC, which are one channel resource, in the same manner as theexisting LTE system in step 944. For example, the reception apparatuscan receive ACK/NACK information using a channel resource, which ismapped to the first CCE of the PDCCH.

When there are two transmission antennas in step 942, the receptionapparatus receives one ACKCH through a plurality of reception antennasusing two CSs and two OCs, which are two channel resources, in step 946.

When there are four transmission antennas in step 942, the receptionapparatus receives one ACKCH through a plurality of reception antennasusing four CSs and four OCs, which are four channel resources, in step948.

In the LTE-A system, the maximum limit of reverse-direction transmissionantennas is set up to be four. Accordingly, as illustrated in FIG. 9D,when the PDCCH has eight CCEs, the reception apparatus selects channelresources that will be used according to the number of transmissionantenna among eight channel resources matched to eight CCEs. When thetransmission apparatus has one transmission antenna, the receptionapparatus receives one ACK/NACK information through a plurality oftransmission antennas using the channel resource matched to the firstCCE in the same manner as the existing LTE system.

When the transmission apparatus uses two transmission antennas, as shownin the above Table 3, one ACK/NACK information is received through twotransmission antennas using two channel resources among eight channelresources.

When the transmission apparatus uses four transmission antennas, asshown in the above Table 4, one ACK/NACK information is received througha plurality of reception antennas using four channel resources amongeight channel resources.

Although embodiments of the present invention have been described indetail hereinabove, it should be clearly understood that many variationsand modifications of the basic inventive concepts herein taught whichmay appear to those skilled in the present art will still fall withinthe spirit and scope of the present invention, as defined in theappended claims.

1. A method of transmitting an uplink ACKnowledge CHannel (ACKCH) for adownlink data channel in a mobile communication system using OrthogonalFrequency-Division Multiple Access (OFDMA), the method comprising:determining channel resources for each Control Channel Element (CCE),when a downlink control channel including at least two CCEs is received;generating uplink acknowledgement information by analyzing a receiveddownlink data channel; assigning the at least two CCEs to at least twotransmission antennas, respectively; and transmitting the uplink ACKCHincluding the uplink acknowledgement information through the at leasttwo transmission antennas.
 2. The method of claim 1, whereintransmitting the uplink ACKCH including the uplink acknowledgementinformation is performed, when a number of the at least two CCEs isidentical with a number of the at least two transmission antennas. 3.The method of claim 2, wherein transmitting the uplink ACKCH includingthe uplink acknowledgement information comprises selecting a number ofthe channel resources corresponding to the number of the at least twotransmission antennas, when the number of the at least two CCEs exceedsthe number of the at least two transmission antennas.
 4. The method ofclaim 2, wherein transmitting the uplink ACKCH including the uplinkacknowledgement information comprises selecting a number of the at leasttwo transmission antennas corresponding to the number of the at leasttwo CCEs, when the number of the at least two CCEs is less than thenumber of the at least two transmission antennas.
 5. The method of claim2, wherein, in a plurality of slots constituting the uplink ACKCH, thechannel resources are differently assigned to the at least twotransmission antennas by slot.
 6. A method of receiving an uplinkACKnowledge CHannel (ACKCH) for a downlink data channel from atransmission apparatus in a mobile communication system using OrthogonalFrequency-Division Multiple Access (OFDMA), the method comprising:transmitting a downlink control channel including at least two ControlChannel Elements (CCEs); selecting a number of reception antennascorresponding to a number of the at least two CCEs and assigning theselected number of reception antennas to channel resources in such amanner that the reception antennas correspond to the channel resourcesby the at least two CCEs, respectively, when the number of the at leasttwo CCEs is equal to or less than a number of transmission antennas ofthe transmission apparatus; and receiving the uplink ACKCH through thereception antennas.
 7. The method of claim 6, further comprising:selecting a number of the channel resources corresponding to the numberof the transmission antennas, when the number of at least two CCEsexceeds the number of the transmission antennas; and selecting thenumber of the reception antennas corresponding to the number of thetransmission antennas and individually assigning the channel resources.8. An apparatus for transmitting an uplink ACKnowledge CHannel (ACKCH)for a downlink data channel in a mobile communication system usingOrthogonal Frequency-Division Multiple Access (OFDMA), the apparatuscomprising: a transmission module for determining channel resources foreach Control Channel Element (CCE) and generating uplink acknowledgementinformation by analyzing a received downlink data channel, when adownlink control channel including at least two CCEs is received; aplurality of transmission antennas for transmitting the uplinkacknowledgement information; and a controller for assigning the at leasttwo CCEs to at least two of the plurality of transmission antennas,respectively, and transmitting the uplink ACKCH including the uplinkacknowledgement information through the at least two of the plurality oftransmission antennas.
 9. The apparatus of claim 8, further comprising adistributor/selector for selecting the at least two CCEs and the atleast two of the plurality of transmission antennas to correspond toeach other in a one-to-one manner, when a number of the at least twoCCEs is identical to a number of the at least two of the plurality oftransmission antennas, under a control of the controller.
 10. Theapparatus of claim 9, wherein the distributor/selector selects a numberof the channel resources corresponding to the number of transmissionantennas, when the number of CCEs exceeds the number of the at least twoof the plurality of transmission antennas.
 11. The apparatus of claim 9,wherein the distributor/selector selects the number of the at least twoof the plurality of transmission antennas corresponding to the number ofthe at least two CCEs, when the number of the at least two CCEs is lessthan the number of the at least two of the plurality of transmissionantennas.
 12. The apparatus of claim 9, wherein, in a plurality of slotsconstituting the uplink ACKCH, the distributor/selector differentlyassigns the channel resources to the at least two of the plurality oftransmission antennas by slot.
 13. An apparatus for receiving an uplinkACKnowledge CHannel (ACKCH) for a downlink data channel from atransmission apparatus in a mobile communication system using OrthogonalFrequency-Division Multiple Access (OFDMA), the apparatus comprising: aplurality of reception antennas for receiving a downlink control channelincluding at least two Control Channel Elements (CCEs) and uplinkacknowledgement information corresponding to the downlink data channelfrom at least two transmission antennas of the transmission apparatus;and a controller for selecting a number of the plurality of receptionantennas corresponding to a number of at least two CCEs, assigning tochannel resources for each of the at least two CCEs, and receiving theuplink acknowledgement information from the uplink ACKCH through theplurality of reception antennas, when the number of the at least twoCCEs is equal to or less than the number of the at least twotransmission antennas.
 14. The apparatus of claim 13, wherein thecontroller selects a number of the channel resources corresponding tothe number of the at least two transmission antennas, selects a numberof the plurality of reception antennas corresponding to the number ofthe at least two transmission antennas, and individually assigns thechannel resources, when the number of the at least two CCEs exceeds thenumber of the at least two transmission antennas.